Go Web Server

1
2    package main
3    
4    import (
5        "context"
6        "encoding/json"
7        "fmt"
8        "log"
9        "net/http"
10        "strconv"
11        "time"
12    
13        "github.com/gorilla/mux"
14    )
15    
16    type User struct {
17        ID    int    `json:"id"`
18        Name  string `json:"name"`
19        Email string `json:"email"`
20    }
21    
22    type Server struct {
23        router *mux.Router
24        users  []User
25    }
26    
27    func NewServer() *Server {
28        s := &Server{
29            router: mux.NewRouter(),
30            users: []User{
31                {ID: 1, Name: "John Doe", Email: "john@example.com"},
32                {ID: 2, Name: "Jane Smith", Email: "jane@example.com"},
33            },
34        }
35        s.setupRoutes()
36        return s
37    }
38    
39    func (s *Server) setupRoutes() {
40        // Middleware
41        s.router.Use(s.loggingMiddleware)
42        s.router.Use(s.corsMiddleware)
43        
44        // Routes
45        s.router.HandleFunc("/api/users", s.getUsers).Methods("GET")
46        s.router.HandleFunc("/api/users/{id}", s.getUser).Methods("GET")
47        s.router.HandleFunc("/api/users", s.createUser).Methods("POST")
48        s.router.HandleFunc("/api/users/{id}", s.updateUser).Methods("PUT")
49        s.router.HandleFunc("/api/users/{id}", s.deleteUser).Methods("DELETE")
50    }
51    
52    func (s *Server) loggingMiddleware(next http.Handler) http.Handler {
53        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
54            start := time.Now()
55            next.ServeHTTP(w, r)
56            log.Printf(
57                "%s %s %s %v",
58                r.Method,
59                r.RequestURI,
60                r.RemoteAddr,
61                time.Since(start),
62            )
63        })
64    }
65    
66    func (s *Server) corsMiddleware(next http.Handler) http.Handler {
67        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
68            w.Header().Set("Access-Control-Allow-Origin", "*")
69            w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
70            w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
71            
72            if r.Method == "OPTIONS" {
73                w.WriteHeader(http.StatusOK)
74                return
75            }
76            
77            next.ServeHTTP(w, r)
78        })
79    }
80    
81    func (s *Server) getUsers(w http.ResponseWriter, r *http.Request) {
82        w.Header().Set("Content-Type", "application/json")
83        json.NewEncoder(w).Encode(s.users)
84    }
85    
86    func (s *Server) getUser(w http.ResponseWriter, r *http.Request) {
87        vars := mux.Vars(r)
88        id, _ := strconv.Atoi(vars["id"])
89        
90        for _, user := range s.users {
91            if user.ID == id {
92                w.Header().Set("Content-Type", "application/json")
93                json.NewEncoder(w).Encode(user)
94                return
95            }
96        }
97        
98        http.NotFound(w, r)
99    }
100    
101    func (s *Server) createUser(w http.ResponseWriter, r *http.Request) {
102        var user User
103        if err := json.NewDecoder(r.Body).Decode(&user); err != nil {
104            http.Error(w, err.Error(), http.StatusBadRequest)
105            return
106        }
107        
108        user.ID = len(s.users) + 1
109        s.users = append(s.users, user)
110        
111        w.Header().Set("Content-Type", "application/json")
112        w.WriteHeader(http.StatusCreated)
113        json.NewEncoder(w).Encode(user)
114    }
115    
116    func (s *Server) updateUser(w http.ResponseWriter, r *http.Request) {
117        vars := mux.Vars(r)
118        id, _ := strconv.Atoi(vars["id"])
119        
120        var updatedUser User
121        if err := json.NewDecoder(r.Body).Decode(&updatedUser); err != nil {
122            http.Error(w, err.Error(), http.StatusBadRequest)
123            return
124        }
125        
126        for i, user := range s.users {
127            if user.ID == id {
128                updatedUser.ID = id
129                s.users[i] = updatedUser
130                w.Header().Set("Content-Type", "application/json")
131                json.NewEncoder(w).Encode(updatedUser)
132                return
133            }
134        }
135        
136        http.NotFound(w, r)
137    }
138    
139    func (s *Server) deleteUser(w http.ResponseWriter, r *http.Request) {
140        vars := mux.Vars(r)
141        id, _ := strconv.Atoi(vars["id"])
142        
143        for i, user := range s.users {
144            if user.ID == id {
145                s.users = append(s.users[:i], s.users[i+1:]...)
146                w.WriteHeader(http.StatusNoContent)
147                return
148            }
149        }
150        
151        http.NotFound(w, r)
152    }
153    
154    func main() {
155        server := NewServer()
156        
157        fmt.Println("Server starting on port 8080...")
158        log.Fatal(http.ListenAndServe(":8080", server.router))
159    }